A fire has torn through a psychiatric hospital in Russia, killing 38 people, many of them in their beds.

The blaze broke out at the single-storey hospital building in the village of Ramensky, 70 miles north of Moscow, at around 2am local time this morning.

There were 41 people believed to be inside the building at the time – 36 patients, three nurses and two doctors.

Only three people – believed to be a nurse and two patients – escaped the fire, prompting speculation the patients were heavily sedated or strapped down and unable to escape.

At least 29 people were burned alive, said Irina Gumennaya, a spokeswoman for the federal Investigative Committee.

The Emergencies Ministry said the patients at the hospital ranged in age from 20 to 76.

Gumennaya told Russian news agencies that most of the people died in their beds.

Blaze: Firefighters battle to tackle the huge fire (Photo: Rex F)

Horrific: Twisted metal frames are all that remains of hospital beds (Photo: REUTERS)

Health Minister Veronika Skvortsova said that half of the patients took sedatives at night.

She insisted that the patients were not tied to their beds and were not given any medication that would leave them unconscious and unable to escape.

Moscow region Governor Andrei Vorobyev said some of the hospital windows were barred.

Investigators believe the fire may have been started by an electrical short circuit. The fire alarm seems to have worked, but the fire spread too quickly.

Officials said it took firefighters an hour to get to the hospital because a ferry across a canal was closed and they had to make a detour.

President Vladimir Putin called for an investigation of the "tragedy", the latest in a long line of disasters at state institutions that are often ill-funded.

Psychiatrists said the fire was not the first and would not be the last of its kind.

"(This happened) because of dilapidated buildings in psychiatric hospitals - a third of the buildings since 2000 have been declared unfit, according to health standards," Yuri Savenko, president of the independent psychiatric association of Russia, said.

Junior and middle-ranking staff had miserable salaries and "because of that the staff were asleep", he said.